As benzoic acid derivative, 2-benzoyloxymethyl-4,6-dihydroxybenzoic acid ethyl ester (refer to Non-patent Document 1), 3-ethyl-4,6-dihydroxy-2-methoxycarbonylmethylbenzoic acid methyl ester (refer to Non-patent Document 2), 3,5,3′-trihydroxybiphenyl-2-benzamide (refer to Non-patent Document 3) are known.
Benzoquinone ansamycin antibiotics such as Geldanamycin and Herbimycin, and Radicicol are known as compounds which bind to heat shock protein 90 (Hsp90) family proteins (Cell Stress & Chaperones, 1998, Vol. 3, p. 100-108; J. Med. Chem., 1999, Vol. 42, p. 260-266). Purine derivatives or pyrazole derivatives are also known as compounds which bind to Hsp90 family proteins (WO03/037860, WO03/055860). These compounds are all reported to bind to Hsp90 family proteins and inhibit the functions of Hsp90 family proteins, thereby exhibiting pharmacological activities such as anti-tumor activity. Therefore, compounds binding to Hsp90 family proteins are considered to be useful as therapeutic agents for diseases associated with Hsp90 family proteins or proteins to which Hsp90 family proteins bind (Hsp90 client proteins).
Examples of known Hsp90 family proteins include Hsp90α protein, Hsp90β protein, grp94 and hsp75/TRAP1 (Pharmacology & Therapeutics, 1998, Vol. 79, p. 129-168; Molecular Endocrinology, 1999, Vol. 13, p. 1435-1448; etc.).
Non-patent Document 1: Journal of the Chemical Society, Perkin Transactions 1, 1979, Vol. 2, p. 529-532
Non-patent Document 2: Tetrahedron Lett., 2000, Vol. 41, p. 4545-4947
Non-patent Document 3: Tetrahedron Lett., 1968, Vol. 8, p. 4919-4924